Why has no one tried to fabricate a new hatch?

[skorpioskorpio]

The more I delve into this the more I think this is something that needs to be done. I think the surface mount glass top with a full glass hatch together with a de-texturing (smoothing) of the top and a one piece glass treatment on the doors would really look slick. I never thought I'd actually be advocating wing window removal but the more I look at it the more limiting mirror placement and choices seems to be. I'm not sure I'm willing to make the leap to suggest modern window crotch mirrors are the ticket, I think maybe that is too far, but I do think bullet type mirrors would look better than those stock type dental mirrors, dysfunctional peeps, or some of these mid sixties uncle Earl's sedan mirrors that together make up 99% of the mirror choices on 67-72s. Lets face it by the time the first gens were done, even Pintos and Vegas had bullet mirrors as an option, it's not unperiod or unbefitting.

[Ebstard944]

I was looking at this thread last week and thinking quite a bit about it. Google formed plexiglass. It seems like it would be stronger, and lighter than fiberglass. Use an original as a pattern for the pieces, or make the outside part all plexiglass, and paint the window out line so you dont see the hardware.

My wife thinks im nuts thinking about this for 3 days.

[skorpioskorpio]

OK, so I had my '91 Suburban broken into twice, opposite coasts BTW, both times it was the vent windows that were broken out. I decided to replace the glass in the vent windows with polycarbonate (Lexan), figured if it can take a bullet it can take a rock or what ever they used (considering how much damage they did getting the radio out I'm guessing rock or maybe brick or parking meter, or some other wildly inappropriate tool). Anyway, point is these non-glass vent windows didn't stand the test of time so well. Makes you realize how abrasive highway speed air is, they pretty much look like frosted glass. Acyclic (Plexiglas) would be a little better, but I doubt by much. There is such a thing as abrasion resistant acrylic but it tends to craze with movement like you would have in a vehicle, it's created by flaming the surface with a very clean burning torch to re-flow the surface. Oh and acrylic won't take a bullet, it splits, easier to break than tempered or laminated glass actually. I think it really needs to be glass.

[scruffyjesse]

Love the 4 piece idea! you would have to make the joints internal other wise it would ruin the lines on the truck. I second the pic notion.

[Ebstard944]

Ok, interesting. But as far as the structure itself (replacing just the fiberglass portion) and just paint it to match the top. Carbon fiber would work, just cost big $. I wonder if you can get lexan in non transparent. It has to be pretty tough, they make airplane windshields out of it.
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[skorpioskorpio]

Yes, you can get opaque polycarbonate, and it can be ordered in shapes as well as sheets. It's tough but not stiff, so you will almost always see it formed into some sort of a stressed curve to help it maintain it's shape. Early WWII canopies were made of Acrylic (Lucite, Plexiglas) not polycarb (Lexan)since polycarb is an invention of the 50s. By the time there is enough structure for either Polycarb or Acrylic, both weigh about the same by volume, to maintain it's shape it would be substantially heavier than fiberglass. It has to be pretty thick in a horizontal plain just to support it's own weight. Neither of these products are a low density or high stiffness material by any stretch of measurement.

The real solution to a strong lightweight top is carbon fiber, ideally as probably an inner formed piece and an outer formed piece with a Styrofoam fill between the two.

Remember carbon fiber is light because it is very stiff and can maintain it's shape while being very thin. The actual resin that holds it all together weighs about the same as fiberglass by volume. The cost in carbon fiber comes from the fact that it needs to be applied in woven sheets and not simply sprayed into a mold like fiberglass, usually by hand or vacuformed. If you don't care about seeing the underlying weave you could probably get it done for a lot less since the process would need to be way less methodical. The material itself is really not that much more expensive if you are talking handlayed carbon fiber vs. handlayed fiberglass, the fiberglass weave is half the cost but you need more layers to get the same stiffness. But even hand layed fiberglass can be made stronger and lighter than sprayed in (like aftermarket caps), in the case of the original tops molded glass filled polyester.

A handlayed fiberglass (again inner and outer foam filled) top could probably be made of equal toughness and rigidity with half the weight, and in carbon fiber half again. Of coarse all this in any material really requires a mold, which I'm somewhat surprised someone hasn't done long ago.

[Ebstard944]

OK, that makes sense. sounds like you have given this alot of thought. Ive had carbon fiber motorcycle parts that have not stood the UV test of time. Im sure paint would solve that. You would think with todays composet material, there would be a way to do it. You are going to have to make the mold Skorpioskorpio. Ill come down and help you make the top. All the rain here, im stuck inside Oct-May!